Slide plate between ski boot sole and ski surface in releasing ski bindings

ABSTRACT

A sliding plate, for use between a ski boot sole and a ski surface in a releasable ski binding, is of the kind comprising a bearer fixable to the ski surface and having a sliding strip mounted at its upper part, and is characterised in that the bearer is formed by a large-surfaced bearing body, relative to said sliding strip, made of a material resistant to mechanical stress, and especially polyethylene resin plastics, and in that said sliding strip is mounted on said bearing body with its surface only slightly protruding above the upper part of the bearing body which surrounds the sliding strip.

United States Patent Beyl June 4, 1974 SLIDE PLATE BETWEEN SKI BOOT SOLE AND SKI SURFACE IN RELEASING SKI BINDINGS 3,448,990 6/1969 Cubbcrley 1280/1135 C Primary Examiner-Richard A. Schachcr Altomey, Agent, or FirmBierman & Bierman [57] ABSTRACT A sliding plate, for use between a ski boot sole and a ski surface in a releasable ski binding, is of the kind comprising a bearer fixable to the ski surface and having a sliding strip mounted at its upper part, and is characterised in'that the bearer is formed by a largesurfaced bearing body, relative to said sliding strip, made of a material resistant to mechanical stress, and especially polyethylene resin plastics, and in that said sliding strip is mounted on said bearing body with its surface only slightly protruding above the upper part of the bearing body which surrounds the sliding strip.

4 Claims, 4 Drawing Figures SLIDE PLATE BETWEEN SKI BOOT SOLE AND SKI SURFACE IN RELEASING SKI BINDINGS The invention relates to a slide plate between a ski boot sole and a ski surface in releasing ski bindings which consists of a bearer attachable to the ski surface with a sliding strip mounted on its upper side.

The release operation of most ski safety bindings is influenced considerably or, in a given case, disturbed by friction occurring between the sole of the ski boot and the ski surface. Since the friction between the ski boot sole and the ski surface depends on the coefficient of friction of the materials lying against each other and on the normal acting force, the friction occurring between sole of the ski boot and the ski surface is considerably influenced by the weight displacement of the skier. During a torsional release of the safety binding a friction can occur, which can inhibit this release so as to prevent it, if the skier loads the ball area of this foot and thus that of the ski boot with his complete weight. Generally one tries to keep this friction, between ski boot and ski, as small as possible and constant or, respectively, at a predeterminable value.

Up till now, two methods have been tried as a solution to the described problem, fistly to provide such sliding devices which try to control the mechanical parts which more relative to each other, and secondly to provide sliding elements in which the magnitude of the occurring friction can be limited to a favourable degree by a corresponding choice of material. In the latter method. however, there exists the difficulty that exactly those materials having a very favourable friction coefficient do not possess sufficient mechanical strength to resist all of the external stresses to which they are sub mitted during falls as well as during fastening and handling of the skis.

The known mechanical sliding devices according to the method first mentioned are very expensive to make and have little resistance to dirt and icing-up. Therefore practice has preferred to choose the second method. For this, sliding elements in the form of sliding strips mounted on the ski surface and made from an extremely low friction material such as tetrafluoroethylene, have become known, which are attached to the ski surface approximatively at the level of the ball of the foot. However, severe problems are created by the permanent mounting of such sliding strips, in particular those made from tetra-fluoroethylen since the mechanical properties of this low friction material are unsatisfactory.

Firstly, one known solution consists of screwing the sliding strip to the ski surface by means of two screws.

This has the severe disadvantage that the heads of these screws protrude out of the surface of the sliding strip when it is loaded, so that the sole of the boots gets caught in the screw-heads and can destroy the sliding action.

Another solution for mounting the sliding strip consists of sticking it onto the ski surface by means of an adhesive. However, tetra-fluoroethylene, which today is considered to have the best sliding properties for the above-mentioned, cannot easily be fixed permanently with adhesives to the ski surface because of its good sliding properties.

Thereforesliding surfaces have been proposed where a thin layer of tetra-fluoroethylene is melted onto an elastic bearer, whereby the bearer is stuck to the ski surface by means of an adhesive. ln practice, this solution has proven unfavourable, since the adhesive could not guarantee a permanent fixture, so that the skier, e.g., in a fall, has lost the sliding strip unexpectedly. However, more serious is the sensitivity of this sliding strip to mechanical damage which still cannot. be avoided. Accidentally knocking against the edge of the sliding strip with a ski when entering the binding cannot be avoided, so that pieces can break off the edge region of the sliding strip or that the complete sliding element can be knocked loose with time. Finally, ski boots mostly have a strongly ridged or profiled sole, so that the necessary slip resistance is obtained when walking on smooth ground. With time this ridging or profiling leaves a strong impression on a slightly thicker or even on a sliding strip, which is melted onto an elastic bearer, made of tetra-fluoroethylene so that the good sliding properties of the sliding properties of the sliding strip are again destroyed.

This object of the invention is to further develop a sliding plate of the above mentioned-type so that, as an element locally fixed onto the ski surface, it can be mechanically very heavily loaded and that it has a sliding surface whose function is not considerably influenced by the loads and stresses imposed on it during skiing.

This problem of a sliding plate of the above mentioned type is solved in that the bearer, which is a large surfaced bearing body as opposed to the sliding strip, is formed from a material, resistant to mechanical loading, especially a plastic made from polyethylene resin, and on which the sliding strip is fixed with its surface protruding only slightly above the upper part of the bearer body which surrounds the sliding strip. The idea on which the invention is based is to introduce a partition of functions regarding the specific stresses to which the sliding plate is subjected during skiing, such that all loadings between the ski boot sole and the ski surface, which are non-sliding loadings are taken up by a material (bearer body) can be heavily mechanically loaded, while all sliding loads between ski boot sole and ski surface are taken up by a sliding strip which is protected against damage. According to the invention this is achieved by the sliding strip protruding only slightly from the upper part of a bearer body having a greater surface than the sliding strip, so that relative to the ski boot surface it is not subjected particularly to mechanical shock and impact stressed as well as oblique loadings during tilting of the ski boot relative to the ski boot surface.

In order to achieve this, the upper part of the bearing body which surrounds the sliding strip is formed, according to the invention, as a support pad which slopes towards the outer edges of the bearing body on at least three sides of the sliding strip.

The sliding strip is appropriately inserted and fixed into a flat excavation of the bearer body. The mounting is preferably undertaken by glueing. The material which is used for the sliding strip namely tetrafluoroethylene, and which as such sticks very badly, has a permanent hold in a sticking compound with the protection of the excavation. The durability of the sliding strip in the bearing body can be further improved by undercutting the side edges of the flat excavation according to the invention and by chamfering the side edges of the sliding strip to suit the undercutting.

The bearing body is given a suitable form in order to take up the different mechanical stressed. The outer edge of the bearing body is formed in the shape of a circular beam curved towards the front grip and formed as a rolling edge situated outside the supporting bulge. The ski boot is tilted on this rolling edge'without damaging the sliding strip during release of the heel grip. If the side edges of the sliding strip, which run transversely to the longitudinal direction of the ski, are, according to the invention, formed in the shape of a circular beam curved towards the front grip, then tilting of the ski boot sole around the rolling edge during release of the heel grip is safely achieved because the radius of curvature of the side edge of the sliding strip and of the adjacent support pad is larger than the radius of curvature of the rolling edge.

Damage to the sliding strip during fastening of the ski is mostly prevented by the fact that the upper part of the bearing body facing the heel grip is according to the invention, designed as a large mounting surface compared to the surface area of the sliding strip which slopes away from the sliding strip or respectively the supporting bulge towards the rear outer edge of the bearing body. During fastening the shoe sole or respectively the front edge thereof slides high over the sliding strip on the entering surface without damaging it.

The large surfaced construction of the bearer body, as compared to the sliding strip, enables it to be provided, according to the invention, at its underside with an adhesive for sticking to the ski surface. The obtained large sticking surface is sufficient for permanent fixing, especially as strong shear-shock loads are mostly avoided by the profile of the bearing body.

Further advantages of the invention are discussed in the following in connection with the description of embodiments of the sliding plate, according to the invention by means of the drawings. I

FIG. 1 shows a plan view of the sliding plate according to the invention;

FIG. 2 shows a section along line B B of FIG. 1

FIG. 3 shows a section along line A A of FIG. 1 and FIG. 4 corresponds to FIG. 3 with undercut excavation.

Bearing body 1 carries a sliding strip 2 which isinserted into its upper part facing the ski boot sole. Bearing body 1 is fixed to the ski surface by means of an adhesive 3. Bearing body 1 has a supporting bulge 4 on its upper part which surrounds sliding strip 2 preferably on all sides.

Sliding strip 2 is inserted into bearing body 1 in a flat excavation 5 and is glued into it. In the embodiment according to FIG. 3, excavation 5 is undercut in order to secure sliding strip 2 even more against coming away.

Further bearing body 1 has an oblique entering surface 6 on its upper part facing the heel grip adjacent to sliding strip 2 or, respectively, supporting bulge 4. The outer edgeof bearing body 1 facing the front grip is designed as rolling edge, 7, adjacent to the supporting bulge 4.

Sliding 'strip 2 consisting of a high quality material with a favourable coefficient of friction is protected in its excavation 5 against mechanical loads, especially those coming from the side, and is thus not damaged. Tetra-fluoroethylene, as such a material which is difficult to glue, as high quality low friction material has a constant hold in a glueing compound with the protection of the excavation above which sliding strip 2 only slightly protrudes. Sliding strip 2 can be very flat, especially when it relates to the low friction but also very expensive tetra-fluoroethylene. Preferably, sliding strip 2, as seen from FIG. 1, is designed in the shape 6f a circular beam curved towards the front grip with its side edges which run transversely to the longitudinal direc tion of the ski boot, whereby the curving corresponds approximately to a radius which the ski shoe makes during a torsional release.

To start with the suitability of profiling bearing body 1 is to be discussed in the following by means of the example of entering the safety binding. When entering carelessly, one does not, with the sliding plate according to the invention, step in front of a sliding strip edge or against another boundary of a sliding element, but the shoe is led by entering surface 6, which forms an entering aid, over and above sliding strip 2,'which protrudes only slightly from excavation 5, into the front griprl-lereby the heel-side edge of sliding strip 2 is protected especially by the supporting bulge 4, which preferably surrounds the rear section of the sliding strip on all sides (Compare-FIG. 3).

Bearing body 1 is formed on the side facing the front grip as a supporting bulge 4 or rolling edge 7 adjacent to it. This rolling edge 7 plays an important part in frontal releases of the safety binding since it fixes the rolling point of the ski boot sole and thereby the length of the lever arm of the sole relative to the heel grip, especially in frontal falls the front edge of sliding strip 2 would beheavily stressed and would be destroyed with time if the heavily profiled or ridged ski boot sole had to roll over it. In the sliding plate according to the invention the sole rolls over the wear resistant rolling edge 7 of the supporting bulge 4.

What I claim is:

l. A sliding plate for use between a ski boot sole and a ski upper surface in conjunction with releasable ski bindings, comprising a bearing body fixedly mounted on the ski surface and made of a material resistant to mechanical stress, the upper surface of said bearing body having a recess, a sliding strip element adapted to be received withinthe recess of said bearing body, the sliding surface of said sliding strip element slightly protruding above theupper surface of said bearing body, the overall surface extension of said, bearing body being substantially greater than the surface extension of said sliding strip element, the areas in the upper surface of said bearing body proximate said recess forming a supporting bulge, said supporting bulge sloping on at least one side of the sliding strip element to the outer edge of said bearing body.

2. A sliding plate as claimed in claim 1 wherein the edge of said bearing body facing the ski tip has the shape of a circular beam curved towar ds said ski tip and forms a rolling edge for the sole of a boot during a skiers fall in the forward direction, said rolling edge being outside and part of the supporting bulge.

3. A sliding plate as claimed in claim 2 wherein edges of the sliding strip transverse to the longitudinal direction of the ski have the shape of a circular beam curved towards the ski tip,- the radius of curvature of said transverse edges and the limiting supporting bulge being larger than theradius of curvature of the front rolling e ge. I

4. A sliding plate as claimed in claim 2 wherein the upper side of the bearing body facing the heel of the ski is designed as a large entering surface relative to the surface area of the bearing body and sloping from the sliding strip and from the supporting bulge towards the rear outer edge of the bearing body. 

1. A sliding plate for use between a ski boot sole and a ski upper surface in conjunction with releasable ski bindings, comprising a bearing body fixedly mounted on the ski surface and made of a material resistant to mechanical stress, the upper surface of said bearing body having a recess, a sliding strip element adapted to be received within the recess of said bearing body, the sliding surface of said sliding strip element slightly protruding above the upper surface of said bearing body, the overall surface extension of said bearing body being substantially greater than the surface extension of said sliding strip element, the areas in the upper surface of said bearing body proximate said recess forming a supporting bulge, said supporting bulge sloping on at least one side of the sliding strip element to the outer edge of said bearing body.
 2. A sliding plate as claimed in claim 1 wherein the edge of said bearing body facing the ski tip has the shape of a circular beam curved towards said ski tip and forms a rolling edge for the sole of a boot during a skier''s fall in the forward direction, said rolling edge being outside and part of the supporting bulge.
 3. A sliding plate as claimed in claim 2 wherein edges of the sliding strip transverse to the longitudinal direction of the ski have the shape of a circular beam curved towards the ski tip, the radius of curvature of said transverse edges and the limiting supporting bulge being larger than the radius of curvature of the front rolling edge.
 4. A sliding plate as claimed in claim 2 wherein the upper side of the bearing body facing the heel of the ski is designed as a large entering surface relative to the surface area of the bearing body and sloping from the sliding strip and from the supporting bulge towards the rear outer edge of the bearing body. 